Solid state electronic technology introduced an incredible reduction in the size of elecronic devices over that of even the tiniest conventional devices. The advent of integrated circuit technology now permits whole circuits to be placed on a thumb-nail sized wafer while complex systems fit on a wafer only an inch or two in diameter. With this incredible reduction in the size of electronic components, manual interfacing devices such as the keys of a pocket calculator are often the devices which limit the practical size of apparatus on which they are used.
In an effort to overcome the size limitations of these manual interfacing devices, it is desirable to improve their electro-mechanical structure so as to reduce their size. These efforts are often blocked by a dramatic increase in cost and difficulty of assembling these small devices.
Examples of apparatus for which it is particularly desirable to reduce the size of manual interaction devices such as switches are electronic watches, subminiaturized calculators, and physiological monitoring equipment. These increasingly popular items must be small to meet their inherent requirements. In the case of watches, their size is further restricted by their competition with the highly developed art of mechanical watchmaking. Competition with mechanical watches also requires that electronic watches be made water resistant, since electronic devices, like mechanical watchworks, are subject to moisture degradation.
One advantage of electronic over mechanical watches is the ability to incorporate additional functions in the electronics of the watch with relatively little increase in the cost of the electronics. For example, watches incorporating date or stop-watch functions may be desired. These additional functions may require switching from the normal time function of the watch to display the additional function. In addition, even electronic watches occasionally need resetting which again requires switching of the time function. Finally, the display of each function of an electronic watch often requires a substantial portion of the power required for operating the watch; therefore, to maximize the life of the power supply for the watch, electronic watches often have switches for activating their function displays only when required.
One prior effort suitable for providing a switch for an electronic watch is shown in U.S. Pat. No. 3,783,607 issued Jan. 8, 1974, in the name of W. A. Feurer. This patent shows a sleeve housing holding a headed actuator. A spring is coiled about a stem of the actuator from a base of the housing to the head of the actuator for resiliently urging the actuator outwardly of the housing. The stem extends through the base of the housing and has a flange outside the housing for retaining the actuator in the housing. A ring gasket extends about the head of the actuator and engages the sleeve of the housing for sealing the arrangement. Not only does this device require inserting the necessarily small actuator within the housing against the action of the spring and the subsequent addition of the flange for retaining the assembly, but it also depends upon the sliding engagement of the ring gasket with the sleeve for retaining its water resistance.